The Light for Night Vision app allows you to use your smartphone as a flashlight of red color light during your session of astronomical observation.

When observing at night with a telescope, you adapt your eyes to the dark environment to perceive a faint celestial object in the field of view of your telescope’s eyepiece. As your eyes become accommodated to night vision, the pupils open widely to collect more light. You may occasionally want to check with a celestial map in the dark, or you may need to illuminate your finders and around to operate the telescope, a camera, and so on. In that situation, the illumination light of a white light flashlight will contract the pupil if it is used. As the result, you will have to wait a short while until the eyes are accommodated to the dark again.

The Light for Night Vision app helps you to keep the ability to see in reduced illumination in the dark by turning the screen on your smartphone into a red light flashlight. The intensity of the red light illumination can be varied brighter or dimmer by swiping up or down on the screen. The brightness setting adjusted is saved for next time use.